Pulled the plugs from my miata and not really sure how bad they look. The number one cylinder plug looks a little crusty, the rest look pretty good.

Here are pics of number 1 and number 2 plugs.

Number 1


Number 1


Number 2


Number 2


I am thinking number one for sure looks a bit too lean. What you guys think?

Afrs are 15.5 cruising, sometimes i would get as low as 12.3 when cruising or slowly acceleration in 2 and 3rd. And sometimes i get as high as 17.5 when just about getting very slowly into boost. I still cant figure out why this is happening. Wot is consistent 11.5-10.8.

 

Dirty injector?

 

Really? Injectors are pretty much brand new 600cc flow tested.

 

If one is lean, then there must be too much air and not enough fuel. Is there any discussion about the OE intake feeding more air to cylinder #1?

It does look lean to me; what if you swap the injector with #2 and see if the condition moves with it? If it does, it has to be the injector. If it does not, perhaps my suggestion on the manifold might be the problem?

 

I will swap the injectors and see if it moves to second cylinder. Btw. Am running e85, so that might cause the sparks to look like I am running a bit lean.

 

I'll be interested with what you find; I'm only supposing that is the cause, I can't imagine another.

 

17.5 moving into boost sounds bad to me. What's the MS programming fix for lean tip in again? I know it's covered in the manual.

I had irregular AFR's showing up, not under your conditions, that turned out to be a bad FPR.

 

Well, Its not just when I am getting into boost but when I am driving with no boost at high rpm.

 

i dont know how mss maps are however you cant up the fuel a bit when at the lower load?

 

I did that and the car feel much better now. Have not checked the plugs yet.

 

just curious how long have you been running it at 17.5? no problems?

 

lol newb use your LC1 more

 

I guess you guys really misunderstood when i meant i run it at 17.5. Lets say i am driving in 3rd gear with vacuum at 10 and start to accelerate very very smoothly with just lightly pressing on the gas. Right when the boost gauge hits about .5PSI my afrs go from 15 to 17.5 and the car starts to lurch a little back and worth, i can keep it like this for a very short time, if i keep accelerating and boost goes to 1psi my afrs go to 12 and if i floor it it does to 11.2 or so. If i am in second and floor the car all the way to 7500 my afrs are instant 10.8-11.5. This is something like a part throttle deal.

 

then richen the fuel in those cells rushin you need more fuel on your boost tip in. So richen up everything 14 kpa below boost a few points and this should help you quite abit. Then tune your cruise cells to 14.5-15-1 for optimal economy.

 

thats exactly what i did. I do it a little bit at a time. I tuned my cruise to 14.5-15.5.